When the notice of vacation follows a notice of abatement, as provided in Section 668.03, such notice of vacation shall not be enforced as provided in this chapter unless the notice specifies a time when the person so notified or ordered may appear before the County Board of Health or officer issuing the same to show cause why such notice should not be issued, and unless the Board, or a majority thereof, or the officer, is present at its or his or her office at the time so specified, such time to be not less than twenty-four hours after the service of the notice. When the notice of vacation is issued, as provided in Section 668.03, without a previous notice of abatement, such notice of vacation shall not be enforced as provided in this chapter unless it specifies a time, not less than five days after the service thereof, when the person so notified may appear before the Board issuing the same to show cause why such notice should not be enforced, and unless the Board, or a majority thereof, is present at its office at the time so specified, provided that when, in the opinion of at least four-fifths of the members of the Board, an emergency exists which requires, for the protection of the health of occupants, the vacation of the building or portion thereof without a delay of five days, then no such fixing of a time for hearing shall be required. (1977 Code Sec. 94.08)